A substantial number of graphic recording systems have been developed to provide automated or computer controlled graphic recording upon a media. While the individual structures of such graphic recorders vary substantially, generally all include a media transport system in which the media is moved in a first direction and a moveable pen carriage supported and controlled to provide motion of the pen carriage in a second direction relative to media motion. In most instances, the directions of media movement and pen carriage movement are orthogonal.
With the development of computer drive systems having increased capability, there arose a need to provide graphic recording systems employing a plurality of recording pens which commonly facilitated multiple color selection.
Several multiple pen graphic recording systems have been developed including that set forth in U.S. Pat. No. 3,401,401 issued Sept. 10, 1968 to Read et al for Multiple Pen Carriage which provides four pens supported on a moveable carriage together with a corresponding group of four independent actuating devices each operative upon one of the pens.
A different approach is found in U.S. Pat. No. 4,135,245 issued Jan. 16, 1979 to Kemplin et al for Plotter With Automatic Pen Changer in which a stationary pen repository holds multiple pens and a moveable recording head configured to receive and support a single recording pen together with means for interrupting the recording process in order to exchange the pen supported by the recording head from the stationary pen repository.
One of the more promising approaches to multiple pen recording is set forth in U.S. Pat. No. 4,578,683 issued Mar. 25, 1986 to Gordon and entitled Graphic Recording System which is commonly owned with the present invention in which a moveable pen carriage supports a plurality of recording elements in a linear array. The carriage is moveable in two directions along a path relative to the recording media and an associated actuator arm mechanism is moveably supported on a rod. The rod has its longitudinal axis generally parallel to the carriage path. Stationary operating means are coupled to the rod and are operative to move the selected pen into engagement with the recording media. Of particular importance is the systems avoidance of powered actuating means upon the pen carriage and its reduction of overall mass of the pen carriage.
Because the change of pens on the linear array requires movement of the pen carriage relative to the pen actuator, there remains a need in the art for a graphic recording system having a lightweight brake mechanism which avoids the need of supporting powered brake mechanisms upon the moveable carriage and provides accurate controllable pen selection and motion.